High voltage temperature switch

ABSTRACT

A high voltage temperature switch for application in either a direct current or an alternating circuit or both and including a body formed of insulating material and defining an arc chute within which a fusible conductor or link is positioned, wherein the link establishes a circuit and opens upon being subjected to a given temperature to interrupt the circuit, and means for generating an electromagnetic field across the arc chute about the fusible link to blow out the arc in the event the link opens.

United States Patent 1191 Fluder [54] HIGH VOLTAGE TEMPERATURE SWITCH [75] Inventor: Chester H. Fluder, .Wheeling, Ill. ['73] Assignee: Vapor Corporation, Chicago, Ill.

[22] Filed: July 16, 1971 52 Us. c1 ..337/282, 200/147 A, 337/165, 337/273, 337/414 [51] 1111. c1. .11011 85/33 [58] Field of Search ..20o/147 A; 335/201; 337/11.0,10s, 166, 135, 273, 232, 401,407,

[56], I j I 1010110 1005 Cited 5 2 UNITED STATES PATENTS 3,613,040 10/1971 Fluder ..337/2s2 2/1903 Maggi .;...200/147A [11] 3,736,544 1 51 May 29, 1973 3,090,854 5/1963 Kretzschmar ..200/l47 A 3,014,109 12/1961 Burger 200/147 A X 2,875,302 2/1959 lmmel et 31.... ..200/l47 A 2,192,059 2/1940 Willmann ..-....335/201 X Primary Examiner-Bamard A. Gilheany Assistant Examiner-A. T. Grimley Attorne'y Marshall J Breen etal.

[57] ABSTRACT A high voltage temperature switch for application in either a direct current or an alternating circuit or both and including a body formed of insulating material and defining an arc chute within which a fusible conductor' or link is positioned, wherein the link establishes a circuit and opens upon being subjected to a given temperature to interrupt the circuit, and

means for generating an electromagnetic field across the arc chute about the fusible link to blow out the arc in the event the link opens.

3 Claims; 4 Drawing Figures HIGH VOLTAGE TEMPERATURE SWITCH This invention relates in general to a circuit breaker or a switch responsive to a high temperature condition to interrupt a circuit and correct the high temperature condition and, more particularly, to a high voltage temperature switch to prevent overheat or fire hazards arising from certain fault conditions, for example, such conditions that may be present on rapid transit cars.

Recent models of rapid transit cars have incorporated evaporators for air conditioning and heaters for heating the compartments as a single package in overhead installations. These heaters produce such a watts density that, in the absence of air flow thereover, considerable damage to equipment and the cars and possibly fire can resulLThe lack of sufficient air flow, when the heaters are energized could be caused by a number of factors, such as broken blower belts, faulty blower motors, badly clogged filters, or welded contacts of a heater contactor. It then becomes a problem to sense the overheat condition and prevent its escalation to the point of damage by interrupting the power source to the heater. I-Ieretofore, there have been a number of devices commercially available and capable of sensing undesirable high temperature and capable of then interrupting light or moderate power sources. These devices are generally referred to as fusible links or heat limiters. However, these devices are not capable of interrupting high voltage circuits in the range of 600 to 750 volts as employed in rapid transit cars.

The present invention relates to a high voltage temperature switch responding to an overheat condition to interrupt a high voltage circuit, and is thereby useful to prevent overheat and fire hazards arising from certain fault conditions on rapid transit cars.

Copending application Ser. No. 009,633 filed Feb. 9, 1970 now US. Pat. No. 3,613,040, issued Oct. 12, 197], discloses a high temperature switch for use in high voltage direct current circuits and reference may be made thereto for details of the structure of the apparatus of that invention. As explained in said copending application, the switch includes fusible link member in the circuit which link member is destructibleor caused to break the circuit when an overheat or faultcondition occurs. When such a condition arises an arc is generated between the released or interrupted end of the fusible link member andadjacent circuit elements. Such an arc is undesirable and means are provided for blowing the arc out which in said copending application takes the form of a magnetic field generated in the arc chute about the fusible link. However, such means are suitable foruse only in a direct current circuit.

Todays requirements in rapid transit cars, for example, may call for the use of both alternating and direct current in the environment where only direct current was previously used. Therefore, new means must be provided for preventing overheat and fire hazards arising from certain fault conditions in a multicurrent circuit environment.

The switch of the present invention includes a molded body of insulating material including an elongated bar'portion and upstanding walls from the bar portion coacting therewith to define an arc chute. Terminals or busses are mounted on the bar in spaced relation and are connected with a fusible link to define a circuit therebetwee'n, which link opens in response tobeing subjected to a predetermined high temperature. The fusible link includes an elongated member of insulated material arched in the center with terminal means fastened to terminal means on one end of the insulating member and releasably fastened on the other end of the member to the other terminal means by a fusible metal.

The leaf spring is bent over the arc portion of the member and, upon being released, will spring up to separate the releasable end from the corresponding terminal means. The fusible metal softens upon being subjected to a given temperature to allow release of the one end of the spring leaf. In order to blow out the arc between the releasable end of the spring leaf and the corresponding terminal means, an electromagnetic field is generated in the arc chute and about the fusible link. Generation of the electromagnetic field is by a pair of electromagnets mounted on opposite sides of the arc chute. When using such an electromagnetic means it is not necessary tobe concerned about the polarity as in thecase of the device of the copending application and also the device of the invention can be used with either alternating or direct current.

It is, therefore, an object of the invention to provide a new and improved high temperature switch capable of interrupting high voltage direct and alternating current circuits.

Another object of this invention is in the provision of a high voltage temperature switch for use on rapid transit cars employing high voltage direct and alternating current circuits to prevent overheat or fire conditions arising from certain fault conditions, and which re sponds to a predetermined high temperature to interrupt the circuit.

A further object of this invention is in the provision of a high voltage temperature switch for direct and alternating current circuits employing a fusible link encased in an insulating material defining an arc chute, and wherein an electromagnetic field is generated in the chute to achieve an adequate interrupting capability.

It is still another object of the invention to provide a novel high voltage temperature switch for use in environments utilizing-both direct and alternating current circuits and wherein polarity of the switch means is not a vital consideration.

Other objects, features and advantages of the invention will become apparent upon reading the following detailed disclosure, taken in conjunction with the accompanying sheet of drawing, wherein like reference numerals refer to like parts, in which:

FIG. 1 is a perspective view of the high voltage temperature switch of the invention;

FIG. 2 is a top plan view of the switch shown in F IG. 1;

FIG. 3 is an end elevational view taken alongline 3-3 of FIG. 2;

FIG. 4 is a fragmentary view, partly in section as taken through the center of the switch on the longitudinal axis and illustrating the fusible link in operative or circuit establishing position and also illustrating the fusible link in circuit interrupting position in phantom.

The high voltage temperature switch of the invention is especially useful for interrupting high voltage direct and alternating current circuits in response :to overheat conditions, although it could also be used wherever there is a need in the electrical circuitry to interrupt a circuit pursuant to a high heat condition. The switch is especially useful in rapid transit cars to protect against damage that might be caused by an electrically powered heater upon the failure of air flow thereover, where the air flow is necessary to maintain the heat condition at the heater within safe limits. Such heaters are powered by high voltage circuits, such as 600 volts or higher, and difficulties are encountered in the interruption of such circuits with commercially available circuit breaking devices. The present invention utilizes a heat sensitive fusible link of a type well known in an environment permitting interruption capability of high voltage circuits, wherein an arc chute is provided in coaction with an electromagnetic field to blow out the arc created during opening of the fusible link.

Referring now to the drawing, the high voltage temperature switch of the invention, generally indicated by the numeral 10, includes a body portion 12 of insulating material formed to define an arc chute 14. A terminal or buss 16 is provided adjacent one end of the switch 10, a terminal or buss 18 is provided adjacent the other end and a fusible link or conductor 20 is provided between the two terminals and in electrical contact therewith.

The switching body 12 may be molded or otherwise formed of a suitable electrical insulating material capable of withstanding temperatures encountered when 7 used in an area to detect a high temperature condition.

For example, the switch would be placed adjacent a heater in a rapid transit .car so that it would sense an overheat condition of the heater and interrupt the circuit of the heater to prevent damage to it and surrounding structure. The body includes a bar portion 22 having an upper substantially flat surface 24and upstanding walls 26 which coact with the flat surface 24 to define the arc chute 14, as illustrated. The configuration of the walls 26 and flat surface 24 is not critical to the invention as long as they coact to define the arc chute 14 within which the fusible link 20 may be positioned.

The terminals 16 and 18 are made of a suitable electrical conducting material, such as copper or the like. The terminals 16 and a8 are respectively substantially rectangular in shape and are fastened to the surface 24 of the switch body by cap screws or the like. The terminal 18 extends into the arc chute 14 as shown in FIG. 2. The terminals 16 and 18 facilitate the connection of the switch into a circuit, as well as connection to the fusible link 20.

The fusible link 20 which completes the switch circuit between terminals 16 and 18 includes an elongated member 28 of suitable insulating material, such as a ceramic or steatite which is supported by terminals 16 and 18 and forms a support for fusible link member 20. As best shown in FIG. 4, metal inserts 30 and 32 are provided in the body 12 for terminal screws 34 and 36, respectively and also for screw 38 said insert for screw 38 not being shown. This insures electrical connection between the fusible link member 20 and the electrical connection at the terminals 16 and 18. The fusible link 20 and insulating block 28 are provided at opposite ends with metal rivets 40 and 42 which electrically connect fusible link 20 to the terminals 16 and 18 respectively. Solder or other suitable means may be employed for connecting the terminals to the rivets and the rivets define a conductive path to the upper side of the memity across the link while the spring steel strip serves to open the link when the link is subjected to a given heat.

The copper strip 44 and the spring steel strip 46 are permanently fastened to the rivet 40 at one end, such as by a suitably solder joint 48, and releasably attached to the other end to the rivet 42 by a heat fusible joint 50. As illustrated, the center portion of the elongated block member 28 is arched upwardly to further facilitate the action of the leaf spring 46 when the heat fusible joint 50 melts, so that the releasable end of the spring member moves upwardly to a position like that shown in phantom in FIG. 4 to thereby break the circuit.

The heat fusible joint 50 is defined by a fusible alloy that is softened upon being subjected to a predetermined heat condition. For example, the melting point of the alloy may define an opening temperature of 140 to 450 F. Therefore, it can be appreciated that current passes through the fusible link 20 and when the fusible link is subjected to a given temperature at which the heat fusible joint 50 will melt, the fusible alloy is softened and the releasable end of the spring pops up to open the circuit established between the terminals 16 and 18 of the switch.

It is characteristic of such switches, when used in high current conditions, that a considerable arc is generated when the current is broken due to overheat conditions as described above. As described above, copending application Ser. No. 009,633, new U.S. Pat. No. 3,613,040, issued Oct. 12, 1971, provides a means for correcting this condition when used in a direct current environment which could not otherwise be corrected. However, since modern conditions in, for example, rapid transit cars, demand the use of both alternating and direct current, the use of that device is limited in its application. In order to correct the high arcing condition in situations, where both alternating and direct current are used, the present invention makes use of an electromagnetic field generated across the arc chute l4 and in the area of the space between the releasable end of the fusible link 20 and the rivet 42 to blow out the arc. Effectively, the electromagnetic field elongates the arc in the blowing out process.

The electromagnetic means 52 includes a pair of electromagnetic coils 54 and 56 arranged on opposite sides of the arc chute l4 and adjacent each wall 26, as illustrated. The coil 54 is formed from and connected to a wire 58, one end of which is connected to terminal 60 to which an outside current source is connected from the circuit of the rapid transit car or other suitable source. The coil 56 is formed from and connected to a wire 62 from coil 54. The end of coil 56 is connected to terminal 18 at screw 36, as illustrated. The coils 54 and 56 are supported on cores or armatures 64 and 66,

only the ends being shown which pass through their respective centers and are maintained thereon by suitable threaded ends and nuts. The electromagnetic assembly is supported on the body portion 12 by a U-shaped bracket 68 and a bolt 70 and nut 72. Thus a circuit is completed through the electromagnetic means 52 by means of a current input at terminal 60, coils 54, 56 and terminal 63, which is connected to the circuit of the rapid transit car or the like, and even though the fusible link 20 is broken there will be a completed circuit through the means 52 to generate and electromagnetic field to blow out the arc.

It is characteristic of the electromagnetic means that the arc will be blown out whether alternating or direct current is used. Further, through the use of an electromagnetic means there need be no consideration of the polarity of the switch as in the case of the use of permanent magneticsused solely in a direct current line. It will be appreciated that, when the fusible alloy is melted and the fusible link opened, an are generated across the releasable end of the fusible link and rivet 42 will be blown out by the field generated by the electromagnetic means 52 to complete the interruption of the circuit. Thereafter, when the fault is alleviated, a new fusible link or switchmay be easily installed without further consideration of polarity since the link is designed such that the releasable end is always in the proper position.

It will be understood that modifications or variations may be effected in the switch of the invention without departing from the spirit and scope of the novel concepts of the invention.

What is claimed is:

l. A high voltage temperature switch for direct and alternating current circuits operable to interrupt the circuit upon being subjected to a given temperature,

' said switch comprising a body of insulating material,

said body having an elongated bar portion and a pair of upstanding substantially parallel and aligned walls intermediate the ends of the'bar and defining therewith an arc chute, a heat fusible link, a pair of terminals disposed adjacent opposite ends of said heat fusible link and operably connected thereto to define a circuit and positioned on said bar portion within said are chute, said heat fusible link including an elongated insulating member arched in the center, terminal means at opposite ends thereof, a leaf spring means permanently attached to one of said terminal means and bent down over the arched center and releasably attached to the other terminal means by a heat fusible metal that is meltable to release one end of the leaf spring means in response to a given temperature, and means generating an electromagnetic field in said are chute about said heat fusible link to blow out an are caused by opening of the heat fusible link, said electromagnetic means including an electromagnet coating with each of said walls to define blow out electromagnetic cavities one on each side of said are chute and arranged to produce an electromagnetic field traversing said are chute, and the area between the releasable end of the leaf spring means in released position and the corresponding terminal means being directly in the path of the electromagnetic field.

2. A high voltage temperature switch as recited in claim 1 wherein said switch is free of any polarity direc tion requirement.

3. A high voltage temperature switch as recited in claim 1 further comprising means for energizing. said electromagnets, when the one end of said heat fusible link is released.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. .3,736,544 Dated May 29, @1973 Invanmr(s) Chester H. Fluder It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The term of this patent subsequent to Signed and sealed this 27th day of May 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents ,Attesting Qfficer and Trademarks FORM PC4050 USCOMM-DC 60376-P69 "I5 GOVEHNHENT PRINTING OFFICE: 93 o UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 736 544 Dated May 29 1973 Inventor(s) Chester H- Elude'r It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The term of this patent subsequent to October 12, 1988, has been disclaimed.

(SEAL) Attest C. MARSHALL DANN RUTH C. MASON Commissioner of Patents and Trademarks Attesting Officer USCOMM-DC 60376-1 69 FORM PC3-1050 (iO-S) u.s covzmmzm PRINTING orrxcs: 93 o 

1. A high voltage temperature switch for direct and alternating current circuits operable to interrupt the circuit upon being subjected to a given temperature, said switch comprising a body of insulating material, said body having an elongated bar portion and a pair of upstanding substantially parallel and aligned walls intermediate the ends of the bar and defining therewith an arc chute, a heat fusible link, a pair of terminals disposed adjacent opposite ends of said heat fusible link and operably connected thereto to define a circuit and positioned on said bar portion within said arc chute, said heat fusible link including an elongated insulating member arched in the center, terminal means at opposite ends thereof, a leaf spring means permanently attached to one of said terminal means and bent down over the arched center and releasably attached to the other terminal means by a heat fusible metal that is meltable to release one end of the leaf spring means in response to a given temperature, and means generating an electromagnetic field in said arc chute about said heat fusible link to blow out an arc caused by opening of the heat fusible link, said electromagnetic means including an electromagnet coating with each of said walls to define blow out electromagnetic cavities one on each side of said arc chute and arranged to produce an electromagnetic field traversing said arc chute, and the area between the releasable end of the leaf spring means in released position and the corresponding terminal means being directly in the path of the electromagnetic field.
 2. A high voltage temperature switch as recited in claim 1 wherein said switch is free of any polarity direction requirement.
 3. A high voltage temperature switch as recited in claim 1 further comprising means for energizing said electromagnets when the one end of said heat fusible link is released. 